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THE AMERICAN COLLEGE OF RHEUMATOLOGY 1990 CRITERIA FOR THE CLASSIFICATION OF VASCULITIS Patients and Methods DANIEL A. BLOCH, BEAT A. MICHEL, GENE G. HUNDER, DENNIS J. McSHANE, WILLIAM P. AREND, LEONARD H. CALABRESE, STEVEN M. EDWORTHY, ANTHONY S. FAUCI, JAMES F. FRIES, RAND1 Y. LEAVI’IT, J. T. LIE, ROBERT W. LIGHTFOOT, JR., ALFONSE T. MASl, JOHN A. MILLS, MARY BETTY STEVENS, STANLEY L. WALLACE, and NATHAN J. ZVAIFLER The American College of Rheumatology Subcommittee on Classification of Vasculitis of the Diagnostic and Therapeutic Criteria Committee developed classification criteria for 7 forms of vasculitis: polyarteritis nodosa, Churg-Strauss syndrome, Wegener’s granulomatosis, hypersensitivity vasculitis, Henoch-Schonlein purpura, giant cell (temporal) arteritis, and Takayasu arteritis. The data collection methods, quality control, and analytic procedures used to derive the classification rules are discussed herein.

ener’s granulomatosis, hypersensitivity vasculitis, Henoch-Schonlein purpura, giant cell [temporal] arteritis, and Takayasu arteritis) were developed by comparing patients who had the particular vasculitis with the remaining group of vasculitis patients. All criteria rules were derived from the same data set, using the same methods. We describe here the methods of data collection, quality control, and analytic procedures that were used to derive the classification rules.

Classification rules for 7 forms of vasculitis (polyarteritis nodosa, Churg-Strauss syndrome, Weg-

Collection of data

From the American College of Rheumatology Subcommittee on Classification of Vasculitis (Diagnostic and Therapeutic Criteria Committee of the Council on Research). Supported in part by NIH grant AM-21393 to ARAMIS. Daniel A. Bloch, P h D Stanford University, Stanford, CA; Beat A. Michel, MD: Rheumaklinik Universitstsspital, Zurich, Switzerland; Gene G. Hunder, MD: Mayo Clinic, Rochester, MN, and Chair, Subcommittee on Classification of Vasculitis; Dennis J. McShane, MD: Stanford University, Stanford, CA; William P. Arend, MD: University of Colorado Health Science Center, Denver, CO; Leonard H. Calabrese. DO: Cleveland Clinic Foundation, Cleveland, OH; Steven M. Edworthy, MD: University of Calgary, Calgary, Alberta, Canada; Anthony S. Fauci, MD: NIAID, NIH. Bethesda, MD; James F. Fries, MD: Stanford University, Stanford, CA; Randi Y. Leavitt, MD, PhD: NIAID, NIH, Bethesda, MD; J. T. Lie, MD: Mayo Clinic, Rochester, MN; Robert W. Lightfoot, Jr., MD: University of Kentucky, Lexington, KY; Alfonse T. Masi, MD, DrPH: University of Illinois College of Medicine, Peoria, IL; John A. Mills, MD: Massachusetts General Hospital, Boston, MA; Mary Betty Stevens, M D Johns Hopkins University, Baltimore, MD; Stanley L. Wallace, MD: SUNY Downstate Medical Center, Brooklyn, NY (Dr. Wallace is deceased): Nathan J. Zvaifler, MD: University of California, San Diego, San Diego, CA. Address reprint requests to the American College of Rheumatology, 17 Executive Park Drive NE. Suite 480, Atlanta, GA 30329. Submitted for publication October 2, 1989; accepted in revised form April 3, 1990.

We developed a data collection form to gather information about the patients to be studied. This carefully designed form was based in part on protocols developed for previous criteria studies by the American College of Rheumatology (ACR) (formerly, the American Rheumatism Association [ARA]). To test the completeness of the form, a retrospective survey was performed on 100 cases of vasculitis drawn from the subcommittee members’ patient files. This step resulted in a revised final data collection form that was 13 pages long and included over 500 items of defined information about each patient. The form included requests for information about the medical history, physical examination findings, laboratory test results, angiogram findings, biopsy results that influenced the diagnosis, treatment, response to treatment, and autopsy findings. ARA classification criteria for scleroderma ( l ) , systemic lupus erythematosus (2). and rheumatoid arthritis (3) were included, as was information regarding other rheumatic diseases and other illnesses.

Arthritis and Rheumatism, Vol. 33, No. 8 (August 1990)

VASCULITIS CRITERIA: PATIENTS AND METHODS Forty-eight rheumatology centers in the United States, Canada, and Mexico were enlisted to contribute cases for study (Table 1). The data collection forms, with detailed instructions about how to use them, were sent to these centers. No criteria or definitions for the diagnosis of a distinct vasculitis were proposed before the study, except that cases entered into the study were to have definite vasculitis. The decision as to which specific type of vasculitis the subject had was made by whatever means were necessary in the judgment of the submitting rheumatologist. Centers were requested to obtain as much information as possible about each patient. It was understood that in most cases, information would not be available to complete all questions on the form (for example, biopsy or angiography would not have been performed on all patients). It was believed that the criteria derived from such “incomplete” data sets would be more generally representative and applicable for clinical use than those derived from “complete” information about every patient. To minimize selection bias regarding typical or atypical cases, disease severity, and other individual factors, we requested that each center collect information on all consecutive patients with any type of definite vasculitis whose first symptom(s) occurred within the previous 2 years. Upon analysis, patients whose symptoms did not fit 1 of the 7 categories of vasculitis studied were placed in the category of “other vasculitis, type unspecified.”

Coding and entry of data From June 1982 through December 1987 (5’/2 years), 1,020 completed forms were returned to I of the participating centers (Mayo Clinic). All forms were reviewed for consistency and possible errors. Questions or ambiguities were referred to the submitting center for clarification. The data forms were then sent to Stanford University to be coded and entered into the computer system. Upon coding, it was found that information on key items, such as sex, age, and diagnosis, was missing from 10% of the 1,020 forms. These forms were sent back to the submitting centers; all were revised and returned to Stanford. Upon completion of coding, the data were entered into the ARAMIS (Arthritis, Rheumatism, and Aging Medical Information System) computer system.

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Selection of potential criteria A subcommittee of the vasculitis criteria subcommittee convened at Stanford University in March 1988. From among the items on which information had been collected, 127 were selected as being potentially important disease discriminators. For a particular category of vasculitis, the study population was divided into 2 groups for each item (at various critical values for nondichotomous items), and univariate assessments of the discriminatory accuracy of individual items were made using a chi-square test for 2 X 2 tables and by considering the sensitivity and specificity of correct classification. Approximately 100 combinations of these 127 items were also selected to be evaluated. These were created by means of Boolean algebra, using union (the combination of 2 items is positive if either item is positive) and intersection (the combination of 2 items is positive only if both items are positive) operations, For a particular item of the respective vasculitis category of interest, sensitivity is expressed as the number of patients within this category who are positive for the item divided by the number of patients within this category in whom this item has been determined. Specificity is expressed as the number of all remaining patients (those with a form of vasculitis different from the one of interest) who are negative or normal for the item divided by the number of such patients in whom the item has been determined. The perfect criterion for the diagnosis or classification of a disease is one that is both completely sensitive (a finding that is present in all patients with the disorder) and completely specific (never present in any other disease), Unfortunately, such criteria do not exist. Usually, the greater the sensitivity of a finding or test, the lower its specificity, and vice versa. When definitions or classifications are to be established for diseases of unknown etiology that are not completely understood and when no pathognomonic test is available, some compromise needs to be made in the degree of sensitivity and specificity of the criteria to be employed. The choice regarding the balance of these 2 factors may be dictated by the projected use of the set of criteria to be formulated. For example, in epidemiologic surveys, it may be desirable to have as criteria for a disease those which have maximum sensitivity and allow moderate specificity, so that all cases are identified. But, for drug trials, maximum specificity and less sensitivity may be suitable. For the 7 studies

Baylor College of Medicine Houston, TX Bowman Gray School of Medicine Winston-Salem, NC Children’s Memorial Hospital Chicago, IL Cleveland Clinic Foundation Cleveland, OH Downstate Medical Center Brooklyn, NY Emory University Atlanta, GA Geisinger Medical Center Danville, PA George Washington University Medical Center Washington, DC Indiana University Medical Center Indianapolis, IN Instituto Mexican0 del Seguro Social Mexico City, Mexico Instituto Nacional de la Nutricion Mexico City, Mexico Johns Hopkins University Baltimore, MD Louisiana State University New Orleans, LA Marshfield Clinic Marshfield, WI Massachusetts General Hospital Boston, MA Mayo Clinic Rochester, MN Montefiore Medical Center Bronx, N Y Mount Sinai Medical Center New York, NY Medical College of Wisconsin Milwaukee, W I Medical University of South Carolina Charleston, SC National Institute of Allergy and Infectious Diseases, National Institutes of Health Bethesda, MD National Naval Center Bethesda, MD Northwestern University Chicago, IL Rheumatolopy Associates Portland, ME

Center, city, state or country Physician

Paulding Phelps, MD

Rowland Chang, MD

Seth Kantor, MD

Randi Leavitt, MD

Bashar Kahaleh, MD

Robert Lightfoot, Jr., MD

Harry Spiera, MD

Arthur Gravel, MD

Gene Hunder, MD

John Mills, MD

William Washington, MD

Joseph Biundo, MD

Mary Betty Stevens, MD

Donato Ala&n-Seg&a,

Gregorio Mintz, MD

John Bradley, MD

Robert Jacobs, MD

Dennis Torretti, MD

Colon Wilson, MD

Joyce Singer, MD

Kenneth Rich, MD and Lauren Pachman, MD Leonard Calabrese, DO

Elliot Semble, MD

Donald Marcus, MD

Table 1. Centers and physicians submitting vasculitis cases

MD

Texas Children’s Hospital Houston, TX University of Alabama at Birmingham Birmingham, AL University of Alberta Edmonton, Alberta, Canada University of Arizona Tucson, AZ University of California, Los Angeles Los Angeles, CA University of California, San Diego San Diego, CA University of Cincinnati Cincinnati, OH University of Colorado Denver, CO University of Connecticut Farmington, C T University of Illinois Chicago, IL University of Iowa Iowa City, IA University of Michigan Hospital Ann Arbor, MI University of Pennsylvania Philadelphia, PA University of Pittsburgh Pittsburgh, PA University of Southern California Los Angeles, CA University of Tennessee Memphis, TN university of Texas Health Science Center at Dallas Dallas, TX Vanderbilt University Nashville, TN Walter Reed Army Medical Center Washington, DC Washington Hospital Center Washington, DC Washington University School of Medicine St. Louis, MO Wayne State University Detroit, MI Wellesley Hospital Toronto, Ontario, Canada William W.Middleton Memorial Veterans Administration Hospital Madison, WI

Center, city, state or country

Walter Sundstrom, MD

Murray Urowitz, MD

Felix Fernandez-Madrid, MD

Jeffrey Kaine, MD

Werner Barth, MD

Richard Welton, MD

Theodore Pincus, MD

James Gilliam, MD

Ramesh Gupta, MD

Rodanthi Kitridou, MD

Leslie Kahl, MD

Robert Zurier, MD

Joseph McCune, MD

Daniel Furst, MD

John Skosey, MD

Arthur Weinstein, MD

Peter Kohler, MD

Alan Solinger, MD

Nathan Zvaifler, MD

Harold Paulus, MD

Terry Weyrauch, MD

Anthony Russell, MD

Graciela Alardn, MD

Donald Person, MD

Physician

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6

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VASCULITIS CRITERIA: PATIENTS AND METHODS reported here, we attempted to derive criteria sets that are equally high in both sensitivity and specificity. The Subcommittee on Classification of Vasculitis convened at the ACR’s May 1988 Annual Meeting in Houston, Texas, and a further subcommittee met at the ACR’s November 1988 Western Region Meeting in Monterey, California, to determine the final list of potentially important discriminators. Twenty-six individual items were added to the original list of 127, and a total of 182 different combinations of the 153 items were considered. The sensitivities and specificities of the 335 potential criteria were then evaluated on a microcomputer, and based on these results, a final “short list” of items for each of the 7 targeted vasculitides was selected. The short-list items represent the most discriminating variables and were further evaluated for inclusion in the classification criteria sets. Depending on the vasculitis category under study, from 4 to 14 items, alone or in combination, were selected.

Selection of study sample and quality control of data After the Stanford meeting (March 1988), each form was reviewed by a subcommittee member (different from the submitting center member) for the presence of enough information to reasonably document the diagnosis assigned by the submitting center physician. For less than 7% of cases, it was thought that the entry diagnosis was not adequately supported; in a small number of cases (20 subjects), the presence of any definite vasculitis was in doubt, based on the data included on the form. With the agreement of submitting center members, these latter 20 subjects were excluded from the data set; the other subjects were classified into their appropriate categories. Among the 1,000 remaining cases, 52 were entered with the diagnosis of Kawasaki disease and 141 as vasculitis with definite underlying connective tissue disease, such as rheumatoid arthritis or systemic lupus erythematosus. For reasons described in the introductory paper by Hunder et al(4), these 193 subjects were also excluded from study. Thus, all subsequent analyses were based on the remaining group of 807 vasculitis patients. Table 2 shows the number of patients in the various categories after the final review. While the numbers reflect the frequency of the occurrence of

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Table 2. Frequency distribution of tvbes of vasculitis* Type of vasculitis Polyarteritis nodosa Churg-Strauss syndrome Wegener’s granulomatosis Hypersensitivity vasculitis Henoch-Schonlein purpura Giant cell (temporal) arteritis Takayasu arteritis Other vasculitis, type unspecified Vasculitis with a connective tissue disease Kawasaki disease Nonvasculitis

No. of cases I IS 20 85 93 85

214 63

I29 141 52 20

* The 48 centers submitted a total of 1,020 cases for these studies. The last 3 groups of patients (n = 213) were excluded from study. these syndromes, as seen in rheumatology centers, the results cannot be considered an epidemiologic profile. The quality of data for the 153 individual items selected for further analyses was checked on 75 data collection forms taken at random from among the 807 forms. Three systematic errors were discovered and corrected: fluorescent antinuclear antibody values had not been coded, alkaline phosphatase values had been improperly coded, and cryoglobulin levels had to be recoded due to the imprecise definition of this item on the data collection form. Upon correction, these 3 variabies were included for the analyses. All laboratory findings were evaluated relative to their normal ranges. Among the remaining 150 items, there were 10 coding errors and 34 data-entry errors. These errors appeared to be random (not systematic), and they represent an acceptable error rate of

The American College of Rheumatology 1990 criteria for the classification of vasculitis. Patients and methods.

The American College of Rheumatology Subcommittee on Classification of Vasculitis of the Diagnostic and Therapeutic Criteria Committee developed class...
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